Modern smartphone devices have settled on a compact and thin format. While this is convenient for the user, both in terms of carrying the device in a pocket and holding it in the hand while in use as a mobile phone it creates difficulties in resolving a high-quality optical image. Thus while the camera modules in today's smartphones have continued to improved in term of pixel resolutions, speed of image acquisition and a wide range of digital manipulation of the underlying image the optical quality is constrained by the physical limitations of the device form factor and the corresponding size of image sensor that can be accommodated within the device.
Some attempts have been made to improve the image quality by providing additional lens elements that clip onto the device over the existing camera lens to increase the zoom, enhance the field-of-view, or to provide improved macro capabilities. However these optical add-on lenses are constrained to the design parameters of the original lens system and the size of the internal sensor element of the smartphone (Dainty 2012).
Some manufacturers have created independent camera modules that communicate with a smartphone via wireless communications such as Wifi (IEEE 802.11). These modules can be attached to the case of a smartphone or may be operated completely independently of the smartphone. They export a control user inferface (UI) for the camera and images are captured in the camera module and compressed to JPEG format (or MPEG format for video) prior to being transferred wirelessly to the controlling smartphone unit.
While these devices can obtain high-quality compressed images and video and may be controlled and operated from the smartphone, they do not support the acquisition of high quality RAW (Bayer) images. Furthermore they require a high-end full imaging system, including dedicated image signal processor (ISP) and main system CPU/GPU and JPEG (images) or MPEG (video) compression engine to be provided within the independent camera module.
With current state of prior art we see that improved imaging can be achieved on handheld imaging devices such as smartphones either by adding (i) an enhanced clip-on lens, or (ii) by connecting a dedicated and fully-independent camera module to the smartphone over a wireless (or wired) link. The first solution is limited by the original optical design and image sensor of the smartphone. The second approach overcomes these limitations but requires a full imaging pipeline and compression engine in order to process and compress images that are suitable for transfer over a wireless link.
Thus there is a need for an add-on peripheral that improves the optical acquisition, and can accommodate a larger sensor size (APC or full-frame) but that can also take advantage of the inbuilt image processing capabilities and system-level ‘apps’ of the smartphone. There is a further need for advanced user interfaces enabling accurate and simplified control of complex digital camera acquisition parameters by users who are not familiar with the operation of advanced DSLR and mirrorless cameras.